Apparatus for applying a metered quantity of adhesive to closures

ABSTRACT

A rotary member having a discharge orifice for dispensing an annular bead of puttylike material upon rotation; the rotary member is mounted for reciprocal movement into and out of a retainer thereby closing and opening the orifice. A material receiving recess in the rotary member is connected to the orifice by a transfer passage. The recess is connected to a supply of material which fills it when the orifice is positioned inside the retainer. It is disconnected from the supply when the orifice is outside the retainer for dispensing at which time any material contained in the recess flows through the transfer passage and is dispensed at the orifice upon rotation of the rotary member.

United States Patent 3,455,275 7/1969 Podesta et a1 ABSTRACT: A rotary member having a discharge orifice for dispensing an annular bead of puttylike material upon rotation; the rotary member is mounted for reciprocal movement into and out of a retainer thereby closing and opening the orifice. A material receiving recess in the rotary member is connected to the orifice by a transfer passage. The recess is connected to a supply of material which fills it when the orifice is positioned inside the retainer. It is disconnected from the supply when the orifice is outside the retainer for dispensing at which time any material contained in the recess flows through the transfer passage and is dispensed at the orifice upon rotation of the rotary member.

PATENTED M1824 I971 I sum 2 or 4 I N VEN TOR jyddf/ BACKGROUND OF THE INVENTION This invention relates to dispensing apparatuses generally and more particularly to apparatus for dispensing beads of adhesives and other puttylike materials around the inside walls of holes and the like. The invention is specifically intended for use on an automobile engine production line for applying beads of adhesive around the inside of holes in engine blocks and heads prior to the insertion of Welch plugs, although it is not limited to that use.

Dispensing such materials on a production line, particularly sealant-type adhesives, presents severe handling problems. This is especially true on an automated line where the leakage of such materials invariably causes fouling and otherwise interferes with the operating parts of the dispensing apparatus itself and with other parts of the production line resulting in costly downtime for cleaning and repair.

In general, the various prior art dispensing apparatuses have suffered from at least two drawbacks. First, relatively high pressures have been used to transfer the material from a supply container through hoses to the dispenser and out of a discharge nozzle or the like. In cases where such apparatus develops a leak, the high pressure distributes the material over a rather wide area around the apparatus and the production line. Also, the pressure at the nozzle tends to cause the material to splatter as it is dispensed.

Secondly, the amount of material dispensed has not been adequately controlled resulting in the application of excessive amounts of material and consequently in needless mess and waste. When materials of the type particularly concerned herein are dispensed by causing them to flow out of an orifice, nozzle or the like, there is always some material remaining inside the nozzle after turnoff. This leftover'inaterial tends to drip and foul the surrounding area.

It is an object of this invention toprovide apparatus capable of operating with little or no direct pressure upon the material to be dispensed.

It is another object of the invention to provide apparatus which dispense and distribute the material by centrifugal force alone without the necessity of pressure on it during the actual dispensing. If a minimal pressure is required to cause the material to flow into the apparatus, that pressure is interrupted during dispensing according to this invention.

It is a further object of the invention to provide apparatus capable of dispensing these materials without the dripping and leakage ofmaterial following dispensing.

It is yet another object of this invention to provide apparatus capable of consistently dispensing measured predetermined amounts of material without the mess and fouling which has occurred heretofore in this art.

It is a still further object of this invention to provide apparatus capable of dispensing annular beads of any desired predetermined size and even the simultaneous dispensing of a plurality of spaced beads having the same or different relative sizes.

SUMMARY OF THE INVENTION These and other objects of the invention are attained by providing an apparatus including a rotary member carried by a retainer means. The apparatus is constructed and arranged to provide reciprocating movement of the rotary member between a retracted position within the retainer means, in which the material to be dispensed is transferred to the rotary member from a supply thereof, and an extended position outside the retainer, in which the material is dispensed by rotation of the rotary member. The rotary member receives material from the supply only when in the retracted position. In the extended position the supply of material is interrupted.

The material is dispensed through a dispensing orifice on the rotary member, the orifice being positioned with respect to the retainer means so as to be closed when the rotary member is retracted andto be open for dispensing when it is extended. The materialflowsout of theorifice when the rotary member is rotated 01' spun while in the extendedposition.

An apparatus in accordance with this invention'will have several advantages over those of 'the prior art. It cannot receive additional material during dispensing and only the 4 material received prior to the extensio'n of rotary member can bedispensed atanyonetirne. i g a I Since all of the material received by the rotary member while it is retracted is dispensed when it'is extended and rotated none of the material will'remain in the rotary member I to leak at a later time. Therefore, there will be no problem with dripping following turnoff or subsequent thereto.

Furthermore, measured predetermined amounts of material may be dispensed and extremely low pressures may be used to cause the material to flow from its supply container to the rotary member. Consequently, if a leak develops somewhere in the supply lines or in the apparatus, it will not cause as great a mess as it would if higher pressures were used. As a result of the positive control over the flow of the material during the operation of the apparatus it may be used at any convenient angle or position without concern over dripping of the material from the rotary member following turnoff.

BRIEF DESCRIPTION OF THE DRAWINGS Other features and advantages of-the invention will be evident from the following description and the drawings in which:

FIG. 1 is a side elevation of a preferred embodiment of an apparatus according to the invention showing the apparatus at rest with the rotary member retracted;

FIG. 2 is a side elevation similar to FIG. 1 showing the rotary member extended such that the apparatus is positioned for dispensing a bead of material inside a hole;

FIG. 3 is a plan view ofthe apparatus shown in FIG. 2;

FIG. 4 is a rear elevation of the apparatus shown in the preceding Figures;

FIG. 5 is a front elevation of the apparatus shown in the preceding Figures; I

FIG. 6 is an enlarged longitudinal sectional view of a forward portion of the apparatus taken along lines 66 in FIG. 5 showing it in the retracted position;

FIG. 7 is an enlarged longitudinal sectional view of a forward portion of the apparatus taken along lines 7-7 in FIG. 5 showing it in the extended position;

FIG. 8 is a sectional view taken along lines 8-8 of FIG. 6;

FIG. 9 is a sectional view taken along lines 9-9 of FIG. 7;

FIG. 10 is a sectional view taken along lines 10-10 of FIG. 7 schematically showing the dispensing and application of a bead of material to the interior wall of a hole;

FIG. 11 is a rear elevation of a preferred embodiment of a rotary member according to the invention;

FIG. 12 is a side elevation of the rotary member shown in FIG. 11, and

FIG. 13 is a fragmentary view of a portion of the rotary member of FIG. 11 taken in the direction indicated by the arrow.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings, particularly FIGS. 1 through 5, a preferred embodiment of an apparatus according to the invention and generally designated as 10 is illustrated. Apparatus I0 is carried on a base II, which may be readily adapted for mounting in any desired position with respect to a production line, workpiece or the like. The apparatus is connected to base 11 by means of two pairs of aligned mounts each being generally designated as 12, which include Thompson roller bearings. Each aligned pair of mounts 12 are respectively arranged onbase 11 to slidably receive guide bars 13 and 14 respectively, which provide a guideway for apparatus 10. Guide bars 13 and 14 together with a first yoke 15, having an upper portion 150 and lower portion b, and a support 16 form a carriage assembly for the working parts of the apparatus.

Yoke 15 is made up of an upper portion 15a and a lower portion 15b which are fastened together by a pair of screws as shown to carry a shaft 18 which may be rotatably enclosed in a sleeve 19 as shown. Sleeve 19 is fixed within yoke 15 by setscrew 20. One end of shaft 18 is coupled at the rear to a means for rotating the shaft such as an air motor generally designated as 21. Air motor 21 is carried by support 16 mounted on sleeve 19, a cantilevered support bar 22 and clamps 23a and 23b. The clamps, as best seen in FIG. 4, have been designed with an inverted V-shaped self-centering lower portion to accommodate air motors of various outside diameters and with an upper portion which may be readily adjusted up or down to various heights by means of two adjusting nuts.

The other end of sleeve 19 carries a helical spring 23 and a retainer means 24. As best shown in FIGS. 6 and 7 retainer means 24 is slidably received upon sleeve 19 by means of a longitudinal bore through the retainer means to enclose end portion 18a of shaft 18 which extends beyond the end of sleeve 19. Sleeve 19 may be fitted at this end with a journal bearing 27. A rotary member 28 is carried by end portion 18a of shaft 18 and by journal bearing 27. Rotary member 28 is fastened to shaft 18 by an end screw 29 so as to rotate when shaft 18 is driven by air motor 21. To facilitate the reciprocating movement or sliding of retainer means 24 back and forth over sleeve 19 it may be provided with a two piece bearing 30 as best shown in FIGS. 6 and 7.

When the apparatus is in a rest position as shown in FIG. 1, a positive refill positioning stop 25 in conjunction with spring 23 resiliently biases retainer means 24 forward against a second stop 36, which consists of an adjustable bolt, thereby placing rotary member 28 in a retracted position inside retainer means 24 as shown in FIGS. 1, 6 and 8.

The apparatus also includes a mechanism, which may consist of any suitable means such as the hydraulic cylinder 37 and an actuating rod 38 interconnecting cylinder 37 to yoke 15, for moving the carriage assembly back and forth along the guideway between a rest position as shown in FIGS. 1, 6 and 8 and a dispensing position as shown in FIGS. 2, 3, 7 and 9.

Stops consisting of a pair of adjustable nuts or the like 40 and 41 carried on a threaded rod 42 on a support 17, are included to provide a limit switch actuator arrangement for operating switches (not shown) or the like which initiate movement of the carriage assembly and the working parts of the machine between the rest and actuated positions by controlling the electrical circuitry which moves the apparatus to its full depth and full return and actuates the filling of the rotary member and spinning thereof.

Referring now to FIGS. 6 through 12, retainer means 24 and rotary member 28 will be described in more detail. Retainer means 24 includes an inlet consisting of aperture 43 and admitting passage 44, as best shown in FIGS. 8 or 9, for conducting material through retainer means 24 to rotary member 28 from an external supply (not shown) which would be connected to fitting 45. Retainer means 24 also includes an outlet consisting ofan exit aperture 46 and exit passage 47 which are oppositely disposed with respect to inlet aperture 43 and inlet passage 44, and which are slightly larger with respect thereto to facilitate the use of the lowest possible pressure or force necessary to cause the material to flow into and out of retainer means 24. By means of annular space 48, best shown in FIGS. 6 and 7, which is formed between rotary member 28 bearing 27 and sleeve 19 on shaft 18, material flowing into retainer means 24 may circulate around the rearward side of rotary member 28 and exit via aperture 46 and passage 47. When rotary member 28 is in the retracted position it is aligned with annular space 48 and inlet aperture 43 and outlet aperture 46 to establish communication therebetween for the flow of material. A line or conduit may be connected to outlet passage 47 by means of fitting 49 to conduct material which has passed through retaining means 24 back to the external supply (not shown).

The flow of material into rotary member 28 is accomplished by a notch or recess or a series of spaced notches or recesses on the sides of the rotary member, all of which are identified in the drawing as 50 and can be best seen in FIGS. 8, 11, 12 and 13. The notches are also preferably situated at the rearward end of the rotary member as shown. At or near an end of each notch is an opening, all of which are identified in the Figures as 51, leading into a transfer passage, all identified in the Figures as 56, which angles outwardly to open laterally on the side of rotary member 28 in a series of spaced discharge or dispensing orifices 57. Puttylike material, such as adhesive and various sealing compounds, received in the notches flows through these transfer passages and out of orifice 57 to be deposited on the interior wall of a hole in the form of an annular bead 58 when rotary member 28 is rotated or spun as shown schematically in FIGS. 2, 3 and 10. Preferably, opening 51 is positioned in the end of the notch toward which the centrifugal force tends to be directed when the rotary member is rotated.

When one notch and corresponding discharge orifice or an aligned plurality thereof as shown in the embodiment disclosed are used, a single annular bead of material is dispensed. However, if the discharge orifices are staggered or unaligned around the exterior surface of the rotary member, a plurality of spaced parallel annular beads may be dispensed. Also, by adjusting the size of the notch or notches and the discharge orifice or orifices, one may dispense beads of a definite predetermined size which contain' any particular amount of material suitable to any particular need.

W|th the various parts and their interrelationship in mind, the operation of the preferred embodiment will now be described. Assume that apparatus 10 is mounted on a production line, for instance an engine headline and that the forward end of retainer means 24 is properly oriented with respect to a hole in an engine head which is momentarily stopped on the line. As is well known, arrangements can be made to cause an article on a line to trip a switch or the like as it moves into a predetermined position and activate a piece of machinery. Such an arrangement in this case would actuate hydraulic or air cylinder 37 causing rod 38 to push the carriage and working parts of the apparatus forward or toward the engine head in conjunction with the limit switch arrangement previously mentioned, retainer means 24 is thus carried forward and pressed against the side of the engine head. At this point spring 23 yields allowing rotary member 28, upon continued movement of the carriage, to enter the hole in the engine block to a predetermined depth. The retainer means having met resistance stops. The forward movement of the forward stop 40 simultaneously actuates a timer arrangement (not shown) which determines and controls the spinning of the rotary member and the duration of its insertion. In the case of puttylike adhesives and sealer compounds, spinning of the retary member at 2,800 r.p.m. is satisfactory. However, the r.p.m. requirement will depend in large part upon the viscosity of the material to be dispensed. The extension of rotary member 28 with respect to retainer means 24 exposes the discharge orifice 57, repositioning notches 50 therein with respect to inlet and outlet apertures 43 and 46 to terminate the supply of material to rotary member 28. In the extended position it is important to the operation of the apparatus that only the discharge orifice 57 be exposed outside the retainer means 24 and the notches 50 be kept within the bore thereof to assure the desired flow of material through the transfer passages 56 and out of the orifice 57 upon rotating the rotary member 28. Since the supply of material is cutoff when rotary member 28 is in the extended position, only the material previously received in the notches can be dispensed. Furthermore, the time of rotation can be adjusted to make certain that all of the material in the rotary member is dispensed. If an engine block or the like is not in position, the rotary member is not extended because the retainer means does not meet a resistance which stops it and allows the continued forward movement of the rotary member. Therefore even if it spins it will not dispense.

Upon beginning return to the rest position with a proper signal from the timer rotation ceases because the control switch is allowed to open. Spring 23 and stop 25 cause retainer means 24 to move forward placing rotary member 28 in the retracted position and realigning notches 50 in gap 48 with inlet aperture 43 so that material can again be supplied to the notches. Rear stop 41 at this point actuates a switch to reapply pressure to the material supply if needed and initiate flow into inlet 43. At this point the apparatus is ready to recycle.

Having described a preferred embodiment of this invention, various modifications will be obvious to those familiar with this art.

What is claimed is:

1. Apparatus for dispensing an annular bead of material around the inside of a hole'or the like comprising:

retainer means including. an interior chamber and an ad mitting passage leading into the chamber for admitting material to be dispensed, and

a rotary member carried by the retainer means at least partially within the chamber for reciprocating movement between a retracted position inside the retainer means and an extended position outside the retainer means, the rotary member having material receiving means comprising a recess for receiving material to be dispensed, the recess being positioned with respect to the chamber admitting passage so as to communicate with it for receiving material when the rotary member is retracted and to be spaced from it for preventing the receipt ofmaterial when the rotary member is extended,

a dispensing orifice on the rotary member positioned with respect to the retainer means so as to be closed when the rotary member is retracted and open for dispensing when it is extended, and

a transfer passage extending between the material receiving recess and the orifice whereby material is transferred to the I orifice and dispensed therefrom when the rotary member is extended and rotated.

2. The apparatus as defined in claim 1 in which:

the retainer means chamber is in the form ofa bore, and

the rotary member is a cylindrical body shaped to fit the bore for both sliding and rotary movement therein.

3. The apparatus as defined in claim 1 in which:

The dispensing orifice is positioned on the side of the rotary member so as to be exposed when in the extended position and to be enclosed in the bore of the retainer means when in the retracted position, and

the transfer passage extends angularly from the recess to the orifice whereby material may flow from the recess through the passage and out the orifice when the rotary member is rotated.

4. The apparatus as defined in claim 3, in which:

a plurality of spaced dispensing orifices are provided on the side ofthe rotary member, and

the rotary member further includes corresponding individual transfer passages and recesses connected to the orifices whereby a predetermined pattern of material may be dispensed.

5. The apparatus as defined in claim 2, in which:

the retainer means bore extends through the retainer means defining front and rear openings therein;

rotary shaft means is provided which is shaped to fit the bore for reciprocating movement therein and is inserted into the bore through the rear opening of the retainer means; and

the rotary member comprises an extension on the shaft, ex-

tending out the front opening of the retainer means to the extended position when the shaft is moved inwardly into the rear opening and retracting into the front opening to the retracted position when the shaft is moved rearwardly out the rear opening.

6. The apparatus as defined in claim 5, in which:

a sleeve is provided which carries the shaft for rotation therein, a forward end portion of the shaft extending beyond the sleeve, the sleeve being shaped to fit the retainer bore for reciprocating movement therein;

the rotary member is carried on the forward end portion of the shaft for rotation therewith and is spaced from the forward end of the sleeve to provide an annular gap therebetween, the gap being positioned relative to the retainer means so as to be aligned with the inlet when the rotary member is retracted;

the retainer means includes an outlet positioned so as to be aligned with the gap when the rotary member is retracted whereby material may enter via the inlet, flow around the gap to fill the recess and exit via the outlet, and

the recess is in the form of a notch at the rear of the rotary member adjacent the gap.

7. The apparatus as defined in claim 6, in which:

the inlets and outlets are oppositely disposed, and

the outlet is larger in diameter than the inlet.

8. The apparatus as defined in claim 6, in which:

the dispensing orifice is positioned on the side of the rotary member so as to be exposed when in the extended position and to beenclosed in the bore of the retainermeans when in the retracted position, and

the transfer passage extends angularly from the recess to the orifice whereby material may flow from the recess through the passage and out the orifice when the rotary member is rotated.

9. The apparatus defined in claim 2, in which:

means is provided for establishing contact between the retainer means and a workpiece having a hole in which an annular bead of material is to be dispensed;

biasing means is provided for yieldably positioning the retainer means and the rotary member relative to each other such that the rotary member may be selectively moved to the extended position with respect to the retainer means when contact is established between the retainer means and the workpiece and the rotary member is extended into the hole.

10. The apparatus as defined in claim 2, in which:

the retainer means includes an inlet for admitting the material to be dispensed;

a shaft'and a sleeve carrying the shaft are provided, a forward end portion of the shaft extending beyond the sleeve;

the rotary member is carried on the forward end portion of the shaft for rotation therewith and is spaced from the end of the sleeve to provide an annular gap therebetween;

the recess is in the form of a notch at the rear of the rotary member adjacent the gap;

the dispensing orifice is positioned on the side of the rotary member;

the transfer passage extends angularly from the notch to the orifice whereby material may flow from the notch through the passage and out the orifice when the rotary member is rotated, and

the retainer means slidably carries the sleeve in the bore such that the annular gap between the rotary member and the sleeve is aligned with the inlet when the rotary member is retracted and such that a workpiece containing a hole to receive an annular bead of material may be brought against a portion of the retainer means to cause sliding movement of the retainer means back along the shaft to expose the dispensing orifice as the rotary member is extended into the hole.

ll. The apparatus of claim 10, in which:

a carriage is provided on which the retaining means and shaft are mounted;

a spring is provided on the shaft between the retainer means and a portion of the carriage for yieldably urging the retainer means forward with respect to the apparatus whereby the rotary member is normally retracted, and

l a stop is provided for positioning the retainer means on the shaft with respect to the rotary body.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 Dated g st 24 1971 Inventor(s) Edward smer It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

On the cover sheet insert [73] Assignee: Chrysler Corporation, Highland Park, Mich.

Signed and sealed this 12th day of September 1972.

(SEAL) Attest:

EDWARD M .FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents 'ORM 5 0-1050 [IO-'59) USCOMM-DC 6US76-P69 v u sv GOVERNMENT PRINTING ormz: I969 o-an-an, 

1. Apparatus for dispensing an annular bead of material around the inside of a hole or the like comprising: retainer means including an interior chamber and an admitting passage leading into the chamber for admitting material to be dispensed, and a rotary member carried by the retainer means at least partially within the chamber for reciprocating movement between a retracted position inside the retainer means and an extended position outside the retainer means, the rotary member having material receiving means comprising a recess for receiving material to be dispensed, the recess being positioned with respect to the chamber admitting passage so as to communicate with it for receiving material when the rotary member is retracted and to be spaced from it for preventing the receipt of material when the rotary member is extended, a dispensing orifice on the rotary member positioned with respect to the retainer means so as to be closed when the rotary member is retracted and open for dispensing when it is extended, and a transfer passage extending between the material receiving recess and the orifice whereby material is transferred to the orifice and dispensed therefrom when the rotary member is extended and rotated.
 2. The apparatus as defined in claim 1 in which: the retainer means chamber is in the form of a bore, and the rotary member is a cylindrical body shaped to fit the bore for both sliding and rotary movement therein.
 3. The apparatus as defined in claim 1 in which: The dispensing orifiCe is positioned on the side of the rotary member so as to be exposed when in the extended position and to be enclosed in the bore of the retainer means when in the retracted position, and the transfer passage extends angularly from the recess to the orifice whereby material may flow from the recess through the passage and out the orifice when the rotary member is rotated.
 4. The apparatus as defined in claim 3, in which: a plurality of spaced dispensing orifices are provided on the side of the rotary member, and the rotary member further includes corresponding individual transfer passages and recesses connected to the orifices whereby a predetermined pattern of material may be dispensed.
 5. The apparatus as defined in claim 2, in which: the retainer means bore extends through the retainer means defining front and rear openings therein; rotary shaft means is provided which is shaped to fit the bore for reciprocating movement therein and is inserted into the bore through the rear opening of the retainer means; and the rotary member comprises an extension on the shaft, extending out the front opening of the retainer means to the extended position when the shaft is moved inwardly into the rear opening and retracting into the front opening to the retracted position when the shaft is moved rearwardly out the rear opening.
 6. The apparatus as defined in claim 5, in which: a sleeve is provided which carries the shaft for rotation therein, a forward end portion of the shaft extending beyond the sleeve, the sleeve being shaped to fit the retainer bore for reciprocating movement therein; the rotary member is carried on the forward end portion of the shaft for rotation therewith and is spaced from the forward end of the sleeve to provide an annular gap therebetween, the gap being positioned relative to the retainer means so as to be aligned with the inlet when the rotary member is retracted; the retainer means includes an outlet positioned so as to be aligned with the gap when the rotary member is retracted whereby material may enter via the inlet, flow around the gap to fill the recess and exit via the outlet, and the recess is in the form of a notch at the rear of the rotary member adjacent the gap.
 7. The apparatus as defined in claim 6, in which: the inlets and outlets are oppositely disposed, and the outlet is larger in diameter than the inlet.
 8. The apparatus as defined in claim 6, in which: the dispensing orifice is positioned on the side of the rotary member so as to be exposed when in the extended position and to be enclosed in the bore of the retainer means when in the retracted position, and the transfer passage extends angularly from the recess to the orifice whereby material may flow from the recess through the passage and out the orifice when the rotary member is rotated.
 9. The apparatus defined in claim 2, in which: means is provided for establishing contact between the retainer means and a workpiece having a hole in which an annular bead of material is to be dispensed; biasing means is provided for yieldably positioning the retainer means and the rotary member relative to each other such that the rotary member may be selectively moved to the extended position with respect to the retainer means when contact is established between the retainer means and the workpiece and the rotary member is extended into the hole.
 10. The apparatus as defined in claim 2, in which: the retainer means includes an inlet for admitting the material to be dispensed; a shaft and a sleeve carrying the shaft are provided, a forward end portion of the shaft extending beyond the sleeve; the rotary member is carried on the forward end portion of the shaft for rotation therewith and is spaced from the end of the sleeve to provide an annular gap therebetween; the recess is in the form of a notch at the rear of the rotary member adjacent the gap; the dispensing orifice Is positioned on the side of the rotary member; the transfer passage extends angularly from the notch to the orifice whereby material may flow from the notch through the passage and out the orifice when the rotary member is rotated, and the retainer means slidably carries the sleeve in the bore such that the annular gap between the rotary member and the sleeve is aligned with the inlet when the rotary member is retracted and such that a workpiece containing a hole to receive an annular bead of material may be brought against a portion of the retainer means to cause sliding movement of the retainer means back along the shaft to expose the dispensing orifice as the rotary member is extended into the hole.
 11. The apparatus of claim 10, in which: a carriage is provided on which the retaining means and shaft are mounted; a spring is provided on the shaft between the retainer means and a portion of the carriage for yieldably urging the retainer means forward with respect to the apparatus whereby the rotary member is normally retracted, and a stop is provided for positioning the retainer means on the shaft with respect to the rotary body. 